Thread tightener



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A, HENNIG THREAD TIGHTENER Filed May 1, 1926 3 Sheets-Sheet 1 INVENTORALBERTJIENMG WITNESSES ATTORNEYS Aprfii 12 9 19270 Filed May 1. 1926 A.HENNlG THREAD TIGHTENER s sheets-sht 2 INVENTOR AL BERTAQi/VNJGATTORNEYS 5 til 12 192?:

" A. HENNHG THREAD TIGHTENER Filed May 1, 19.26 3 Sheets-$21961: 3

WITNESSES m W 1% I, W. 5V 5B L A Patented Apr. 12, 1927.

UNITED STATES PATENT OFFICE.

ALBERT HENNIG, OF BIELEF-ELD, GERMANY, ASSIGNQR TO ANKER-WERKE AKTIEN-GES-ELLSCHAFT, 0E BIELEEELD, GERMANY.

THREAD TIGHTEN Application filed May 1, 1926, Serial No. 106,077, "andin Germany November 4, 1924.

The present invention relates to improvements in thread tightens-rs. andis part1cularly adapted for use with buttonhole-sewing machines havingautomatic thread cutters in which the shears after cutting the threadsare swung sidewise out of the cloth pressure apparatus.

With machines of this character, it is essential that the thread befirmly tightened at the time when the shears holding the out thread areswung back in order to take as much loose thread as necessary for thebeginning of the next buttonjhol'e; that is to say, to have as muchloose thread as the shears need for their swinging movement,

and as is necessary for the proper nctio ning of the first stitch at thebeginning of the next buttonhole.

In accordance with the present invention 1 accomplish this result by theprovision of a thread tightening lever, to which a swinging movement isgiven when the coth clamp is opened after the cutting of the upperthread. This lever draws the thread off to the side between the pressureapparatus and the thread carrier after the clamping of the pressureapparatus is relieved.

I have shown the apparatus as attached to a conventional type ofbuttonhole sewing machine, although obviously it might, with slightvariations, be attached to other sewing machines.

The invention may be more fully understood from the followingdescription in connection with the accompanying drawings, wherein- Fig.1 is a view in side elevation of a sewing machine embodying the presentinven tion.

Fig. 2 is a fragmentary side elevation looking at the machine from theopposite side.

Fig. 3 is a sectional plan view through the machine.

Fig. 41- is a plan of the head of the machine.

The upper thread 10 runs in the well known way. from the tension discsa, over a fixed thread hook r, and tightening spring a, to the threadcarrier g swinging up and down. I provide means for relieving at timedintervals, the thread clamping action of the tension discs a. This meansmay conveniently be. in the nature of an arm 6 mounted on a rock shaft0, journalled transversely of the head of the machine. The arm Z2 isprovided with a wedge shaped nose 6 adapted to enter between theclamping device a, consisting of two discs a a having conical flanges,loosely aranged on a fixed threaded pin a and pressed together byconical spring a against which the curled nuta* of the pin 64 works.When the noise Z) of the arm '2) is pressed between the two discs a anda the tension of the thread 10 is relieved.

The other end of the rock shaft 0 carries an arm cl, pivoted as at e, bya ball and socket joint to the forked end f of a curved anr n f. Arm isconnected to one end of a shaft g, journal-led longitudinally of themachine in suitable bearings g. The oppositc end of the shaft 9 is rigidwith a crank arm it carrying at its free end a pin a, which can beshifted against the pressure of a spring (not shown) arranged in boss72. of the arm It. The pin 71 rests against the rear side of an arm Zconnected with a not shown lever for the knife for cutting thebuttonhole and this arm Z guides the stop pin 00 of the stopping andstarting lever 70. To the crank arm in is connected a spring m, theother end of which is fastened to the under end of the stopping andstarting lever 70. This arrangement is generally known, so that afurther description seems not to be necessary.

Arm Z is moved downward in the well known way, when the stopping andstarting lever is is swung backwards after a buttonhole is finished,thus permitting the pin 2' under the influence of its spring to catchover the arm Z. When the stop pin 00 moves upward again in order to stopthe main driving shaft the pin '5 is taken along, and the crank h isswung upwards, so that by shaft g, curved arm f, arm (Z and shaft 0 thearm I) is swung against the tension device a, so that the wedge shapednose 6 of the arm 0 is pressed between the tension discs a a and spreadsthem, whereby to reliei ten sion on the thread 10.

The shaft 0 also carries a tightening lever 0. This lever is rotatablymounted on the shaft, and is normally spring held in the position ofFig. 2 by a coiled contractile spring 0. The lever 0 carries at itsupper end a strap 2, through which the thread 10 passes. The lower endof lever 0 rests upon the forward end of the tilting cloth clamp 11,

beneath which the automatic shears u of conventional construction aredisposed.

After finishing the buttonhole, the rear end of the cloth clamp ispressed downwardly in the conventional manner tilting the front endupwardly to permit movement of the cloth. At this time the shears areactuated to cut the thread. Simultaneously the lever 0 is moved to thedotted line position of Fig. 2, whereby the thread strap 7) draws thethread sidewise between the tensioning discs 0 and the thread carrier g,providing considerable slack in the thread. This slalck accommodates forthe return movement of the shears a, when swinging back from the clothpressure apparatus after cutting the thread.

Various changes and alterations might be made in the general form andarrangement of parts described without departing from the invention.Hence I do not wish to limit myself to the details set forth, but shallconsider myself at liberty to make such changes and alterations asfairly fall within the spirit and scope of the appended claims.

I claim:

1. The combination with a sewing machine including a tilting clothclamp, of a pivoted thread pulling lever having at one end a memberthrough which the thread passes and having its other end normallyresting directly on the cloth clamp and actuated by movement thereof toproduce slack in the thread.

2. In a sewing machine, the combination with a cloth clamp, of a pivotedthread pulling lever having its lower end normally resting on the clothclamp and actuated thereby, and a loop carried by the upper end of thesaid lever and through which the thread passes.

In a sewing machine, the combination with a cloth clamp and a threadte-nsioning device, of a rock shaft, an arm mounted on the rock shaftfor rendering the tension device inoperative, and a pivoted and springpressed thread pulling lever mounted on the said rock shaft and havingits lower end engaging the cloth clamp and actuated thereby, and a loopat the upper end of the said lever and through which the thread passes.

In testimony whereof I have signed my name to this specification.

ALBERT HENNIG.

